Lamp control system for automatically controlling the cooling blower



LAMP CONTROL SYSTEM FOR AUTOMATICALLY CONTROLLING THE COOLING BLOWER Filed April 22, 1966 Dec. 19, 1967 w. N.SCHEPPE 3,359,454 I FIG. I 13 I9 w I LIGHT 22b 43 INTEGRATOR SLOW T0 CLOSE I 35 30 INVENTOR:

WILLIAM N. SCHEPPE ATT'YS United States Patent 3,359,454 LAMP CONTROL SYSTEM FOR AUTOMATICALLY CONTROLLING THE COOLING BLOWER William N. Scheppe, Chicago, Ill., assignor to The Nuarc Company, Chicago, 11]., a corporation of Illinois Filed Apr. 22, 1966, Ser. No. 544,539 9 Claims. (Cl. 315-117) ABSTRACT OF THE DISCLOSURE I An improved circuit controls the operation of a mercury vapor lamp for effecting the proper cooling of the lamp.

The mercury vapor lamp is rapidly cooled when it is off to minimize the restart or recycle time. Moreover the lamp is not force cooled during its warming up period thus providing for warmup in the minimum time. A first relay is provided for cutting out the lamp cooler fan when the lamp is started up. A second relay which is slow to close is provided for restarting the lamp blower after a predetermined time delay upon starting of the lamp. The fan blower may be of the two-speed type so that the most rapid cooling is obtained when the lamp is off.

The present invention relates to a lamp control system for high intensity lamps and, more particularly, to a system for controlling the cooling of high intensity lamps such as may be used in a plate maker or other photocomposing machine which requires a very high level of illumination.

Because of the very high levels of illumination required in the photocomposing field, mercury vapor lamps have become a desirable source of illumination. However, mercury vapor lamps have certain characteristics which are undesirable in a plate making device. More specifically, the slow starting characteristic inherent in mercury vapor lamps presents undue delay to the operator. Similarly, the long delay between the shutoff time and the time to restart the lamp to allow for tube cooling presents undesirable delays. The change in the exposure time required to compensate for the variation in light output of the lamp due to the age of the lamp, the lamp voltage and variation in starting time also presents some difficulty.

The slow starting characteristic inherent with mercury vapor lamps can be overcome by applying extra starting power to the lamp so that, for example, by applying 1500 watts of power to a 750 watt mercury vapor tube, the

starting time can be reduced by approximately twenty to forty seconds. However, once the lamp is heated up, it tends to overheat due to the excess wattage which must be dissipated. Overheating of the lamp in turn will cause extremely short lamp life accompanied by very rapid darkening of the lamp and reduced light output during its life. Also, overheating of the lamp makes it possible for the lamp to get hot enough to soften the quartz tubing forming the lamp envelope.

The time necessary to restart the lamp after it is once blighted and shut off is determined by the loss of lamp heat when deenergized. The cooler the lamp, the easier it V is to start, since the vapor pressure is a function of the lamp temperature. By forced air cooling, the lamp can be restarted in approximately thirty to forty seconds.

i The change in light output of the lamp can be compensated for by a device called a light integrator which comprises a conventional integrating circuit employing a known type of light cell. This device will compensate for the change in light output by increasing or decreasing the time of exposure thereby producing uniform photographic results.

Accordingly, it is an object of the present invention to provide a new and improved lamp control system which overcomes the above-mentioned difficulties.

Yet another object of the present invention is to provide a lamp control system for cooling mercury vapor lamps of the type used in the photocomposing arts.

Yet another object of the present inventon is to provide a new and improved lamp cooling system which reduces the starting time of the lamp.

Yet another object of the present invention is to provide a neW and improved lamp cooling system which minimizes the restarting time for restarting a lamp.

Yet a further object of the present invention is to provide a new and improved lamp cooling system.

In accordance with these and other objects, there is provided an improved lamp cooling system wherein a blower is provided for forcing cooling air over the lamp when the lamp is oil and provided with a suitable control device to shut the blower completely off while the lamp is being started. During the starting period of the lamp, maximum heating of the lamp is desired to bring the lamp to full intensity as fast as possible. This lamp circuit is also provided with a time delay relay which is adjusted to start operating when the lamp is first turned on. The delay time is set to approximately coincide with the time required for the lamp to get up to full operating power. When this relay operates, it bypasses the aforementioned blower cutoff device.

The lamp cooling circuit used, if desired, can be connected to apply full voltage to the blower motor when the lamp is off, and some fractional voltage when the lamp is lit. In a preferred embodiment where the blower motor is selected to be of a type whose speed is a function of input voltage (shaded pole, series, and the like), the blower can be adjusted to operate at a speed that will cause enough lamp cooling to prevent the problems of an overheated lamp without over-cooling of the lamp which in turn would cause the lamp Wattage and light output to be reduced after the blower was turned on. Moreover, although the preferred embodiment employs a time-delay mechanism to control the cooling blower, there are other devices which could perform equally well, such as a current sensitive device in the lamp circuit or light sensitive device in close proximity to the lamp.

For a better understanding of the present invention, reference may be had to the accompanying drawing wherein:

FIG. 1 is a schematic view of a control system for a lamp cooling blower according to the: present invention; and

FIG. 2 is a somewhat schematic view of a lamp, blower, and reflector combination in accordance with the present invention.

Referring now to the drawing, there is illustrated a control system for an air-cooled electric lamp of the type suitable for use in the photocomposing field in accordance with the present invention and adapted to operate an electric lamp 10 and a blower 12 from a suitable source of electrical energy, here illustrated as a two-phase alternating current supply 13, 14. The lamp 10 is of the known mercury vapor type which provides a high intensity illumination for photocomposing and the like.

As best illustrated in FIG. 2, the blower 12 is positioned with an air discharge 12a to direct cooling air against the lamp 10. A reflector 15 serves to direct the light rays in the desired direction and at the same time to provide a deflector for the cooling air.

Referring again to the circuit of FIG. 1, the control system according to the present invention includes a pair of line fuses 17, 18 in the respective power lines 13 and 14 ahead of a main switch illustrated as a double-pole single-throw switch 19. The main switch 19 is effective when closed to provide power to the components of the control system, and when open to render the cooling system and lamp ineffective.

To provide for an instantaneous push-button ignition of the lamp 10, there is provided a holding relay 22 of the double-pole type which is energized when it is desired to light the lamp 10. Closing of a push-button switch 23 energizes the holding relay 22 and closes a pair of relay contact blades 22a, 22b to connect a pair of control lines 24, 25 to the power lines 13, 14. The lamp is connected across the control lines 24, 25 through a suitable lamp power supply 26 so that the lamp 10 is energized whenever the holding relay 22 is energized. The lamp power supply may be of a conventional type including a power transformer 27 and a power capacitor 28 serially connected to the lamp 10.

To provide for locking in of the holding relay 22 for the desired period, and then to deenergize the holding relay 22 after a predetermined light output by the lamp 10, there is provided a light integrator 30 illustrated in the broken line box of FIG. 1 and having a known light integrator circuit. The light integrator 30 includes a pair of power contacts 31 externally connectable to power terminals 32 and 33. In addition, there is provided external control terminals 34 and 35 to the light integrator circuit. As is known in the art, the light integrator 30 includes a suitable light cell which receives the light output from the lamp 10 and integrates the light output so as open the power contacts 31 after a predetermined total light output by the lamp 10. In one embodiment, the light cell was a No. 4404 RCA. cadmium-sulfide photoconductive cell. The power contacts 31 are normally closed so that initial instantaneous closing of the push-button switch 23 which is effective initially to energize the holding relay 22 will energize the light integrator and will thereafter connect power to the holding relay 22 from the control line 24 through the power contacts 31 so as to lock in the holding relay 22 so long as the relay switch blades 22a, 22b and the power contacts 31 remain closed. It will be understood that once the power contacts 31 of the light integrator 30 open under the influence of the light integrator circuit, the holding relay 22 will become deenergized, opening the relay switch blades 22a and 22b, and turning off the lamp 10.

To provide for control of the light integrator circuit 30, the control terminals 34 and 35 are connected across the control lines 24 and 25 by suitable conductors 37, 38 so that the control circuit of the light integrator is energized upon initial closing of the push-button switch 23, but is activated by the light output of the lamp 10 to open the power contacts 31 after a predetermined light output.

Referring now to the blower 12, whenever the holding relay 22 is deenergized, the blower 12 is connected directly across the power lines 13 and 14 through suitable conductors 39, 40, and 41. In this manner the full line voltage is provided to the blower 12 when the lamp 10 is shut off so as to rapidly cool the lamp 10 and minimize the restart time of the lamp. However there is provided a blower relay 43 connected to open a relay contact 43a in the blower circuit as soon as the holding relay 22 is energized. In this manner the blower 12 is cut off from the full line voltage of the power lines 13 and 14 by the blower relay 43 whenever the holding relay 22 is energized.

In order to hold the blower 12 in an off condition during starting of the lamp 13, and thereafter to turn on the blower 12 at a reduced speed, there is provided a slow-to-close relay 45 which is energized whenever the holding relay 22 is energized. The slow-to-close relay 45 includes a relay switch 45a which is normally open, and which closes after a time approximating the time that it takes for the lamp 10 to come to the desired level of illumination. So long as the relay switch 45a is open, the blower 12 is not energized through the relay 45. It is understood, however, that when the holding relay 22 is also deenergized, the blower 12 is then connected cross the full line voltage of the power lines 13 and 14 through the blower relay 43. However, once the holding relay 22 has been energized by depression of the push-button switch 23, the relay 43 is open, and during the initial delay period thereafter the relay 45 is also open, so the blower 12 will shut down. After the expiration of the desired delay period, the relay switch 45a will close, connecting the blower 12 across the power lines 13 and 14 serially with a voltage dropping re sistor 46 to provide a reduced voltage for operating the blower 12 at a reduced output.

From the foregoing detailed description, the operation of the lamp cooling system according to the present invention is believed clear. However, briefly, it will be understood that the blower 12 is energized whenever the main switch 19 is closed. Such energization of the blower 12 takes place through the relay 43 to apply the full line voltage to the blower 12 so that the blower 12 runs at its maximum speed and provides maximum cooling for the lamp 10. However, once ignition of the lamp 10 has been initiated by actuation of the instantaneous switch 23 and energization of the holding relay 22, the blower relay 43 will actuate to open the relay switch 43a and remove the blower 12 from directly across the power lines 13 and 14. At the same time initial energization of the holding relay 22 is effective to energize the lamp 10 through the power supply 26. The holding relay 22 will be locked in energized condition by the light integrator 30 until such time as the light output of the lamp 10 actuates the light integrator to open the power contacts 31 and deenergize the relay 22. Moreover, it is understood that initial energization of the holding relay 22 is efiective to energize the slow-to-close relay 45 so that during the initial lamp starting period the blower 12 is completely shut down and the lamp 10 may proceed to the desired level of illumination in a minimum period. The delay period of the slow-to-close relay 45 is approximately that of the time period required for the lamp 10 to come to the desired level of illumination. However, once the relay switch 45 actuates to connect the blower 12 serially with the voltage dropping resistor 46 across the power lines 13 and 14, the blower 12 will then become effective to cool the lamp 10 at a reduced rate due to the reduced voltage being applied to the blower 12.

Advantageously applicants invention provides for forced air cooling of the lamp when the lamp is oil, but the relays 43 and 45 are eflective to shut off the blower completely when the lamp is starting. In this manner the starting time of the lamp is minimized, and at the same time the restarting time of the lamp is also minimized. Moreover, the cooling rate of the lamp while the lamp 10 is lit is controlled by applying a reduced voltage to the blower 12 so that the lamp is neither over-cooled nor under-cooled; on the other hand, by applying the full line voltage to the blower 12 when the lamp 10 is shut off results in maximum cooling of the lamp 10 during its shutoff period thereby to reduce the restarting time.

Although the present invention has been described by reference to only a single embodiment thereof, it will be apparent that numerous other modifications and embodiments may be devised by those skilled in the art, and it is intended by the appended claims to cover all modifications and embodiments which will fall within the true spirit and scope of the present invention.

What is claimed as new and desired to be secured by Letters Patent of the United States is:

1. A control system for an air cooled electric lamp adapted to operate the electric lamp from a source of electrical power and comprising:

a lamp power supply for operating an electric lamp;

a lamp cooling blower for directing cooling air against alamp;

contact means movable between an on and an oil position adapted to electrically connect said lamp power supply across a source of electrical power to control energization of said power supply between an on and an off condition; and

a slow-to-close relay energized upon movement of said contact means to an on position to energize said blower after an initial delay period.

2. A control system as set forth in claim 1 and including photo-integrator means for automatically opening said contact means after a desired quantity of light has been provided by the lamp.

3. A control system for an air cooled electric lamp adapted to operate the electric lamp from a source of electrical power and comprising:

a lamp power supply for operating an electric lamp;

contact means movable between an on and an off position adapted to electrically connect said lamp power supply across a source of electrical power to control energization of said power supply between an on and an oil? condition;

a lamp cooling blower normally directing cooling air against a lamp when the lamp circuit is deenergized with said contact means in an off position and energized through a circuit including a normally closed relay switch and said contact means; and

means controlling said relay switch responsive to move ment of said contact means to an on position to open said relay switch and thereby cut out said blower so that said lamp warms up rapidly without the cooling effect of said blower.

4. A control system as set forth in claim 3 and including photo-integrator means for automatically opening said contact means after a desired quantity of light has been provided by the lamp.

5. A control system as set forth in claim 3 and including a slow-to-close relay energized upon movement of said contact means to an on position to energize said blower after an initial delay period.

6. A control system for an air cooled electric lamp adapted to operate the electric lamp from a source of electric power and comprising:

a lamp power supply for operating an electric lamp;

a two-speed blower for directing cooling air against a lamp;

lamp contact means movable between an on and an oil position adapted to electrically connect said lamp power supply across a source of electrical power to control energization of said power supply between an oil and an on condition;

high speed circuit means including high speed contact means connected to operate said. blower at a high speed;

low speed circuit means including low speed contact means connected to operate said blower at a low speed; and

speed control means responsive to energization of said lamp power supply connected to render said high speed circuit means effective when said lamp power supply is deenergized and to render said low speed circuit means effective when said lamp power supply is energized.

7. A control system as set forth in claim 6 and including photo-integrator means for automatically opening said contact means after a desired quantity of light has been provided by the lamp.

8. A control system as set forth in claim 6 wherein said speed control means includes a slow to close time delay relay in said low speed circuit means so as to provide a delayed operation of said blower upon initial energization of said lamp power supply and thereafter effective to connect said blower with said low speed circuit means.

9. A control system as set forth in claim 8 wherein the time delay of said relay is approximately equal to the period of time required by the lamp to come up to the desired level of output.

References Cited UNITED STATES PATENTS 5/1937 Bunger et al 315-117 4/1942 Dunham et al. 315-117 

6. A CONTROL SYSTEM FOR AN AIR COOLED ELECTRIC LAMP ADAPTED TO OPERATE THE ELECTRIC LAMP FROM A SOURCE OF ELECTRIC POWER AND COMPRISING: A LAMP POWER SUPPLY FOR OPERATING AN ELECTRIC LAMP; A TWO-SPEED BLOWER FOR DIRECTING COOLING AIR AGAINST A LAMP; LAMP CONTACT MEANS MOVABLE BETWEEN AN ON AND AN OFF POSITION ADAPTED TO ELECTRICALLY CONNECT SAID LAMP POWER SUPPLY ACROSS A SOURCE OF ELECTRICAL POWER TO CONTROL ENERGIZATION OF SAID POWER SUPPLY BETWEEN AN OFF AND AN ON CONDITION; HIGH SPEED CIRCUIT MEANS INCLUDING HIGH SPEED CONTACT MEANS CONNECTED TO OPERATE SAID BLOWER AT A HIGH SPEED; LOW SPEED CIRCUIT MEANS INCLUDING LOW SPEED CONTACT MEANS CONNECTED TO OPERATE SAID BLOWER AT A LOW SPEED; AND SPEED CONTROL MEANS RESPONSIVE TO ENERGIZATION OF SAID LAMP POWER SUPPLY CONNECTED TO RENDER SAID HIGH SPEED CIRCUIT MEANS EFFECTIVE WHEN SAID LAMP POWER SUPPLY IS DEENERGIZED AND TO RENDER SAID LOW SPEED CIRCUIT MEANS EFFECTIVE WHEN SAID LAMP POWER SUPPLY IS ENERGIZED. 